/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.skfiy.util;

import java.io.Serializable;

/**
 * Simple customizable helper class for creating threads. Provides various bean
 * properties, such as thread name prefix, thread priority, etc.
 *
 * <p>Serves as base class for thread factories such as
 * {@link org.springframework.scheduling.concurrent.CustomizableThreadFactory}.
 *
 * @author Juergen Hoeller
 * @since 2.0.3
 * @see org.springframework.scheduling.concurrent.CustomizableThreadFactory
 */
@SuppressWarnings("serial")
public class CustomizableThreadCreator implements Serializable {

    private String threadNamePrefix;
    private int threadPriority = Thread.NORM_PRIORITY;
    private boolean daemon = false;
    private ThreadGroup threadGroup;
    private int threadCount = 0;
    private final Object threadCountMonitor = new SerializableMonitor();

    /**
     * Create a new CustomizableThreadCreator with default thread name prefix.
     */
    public CustomizableThreadCreator() {
        this.threadNamePrefix = getDefaultThreadNamePrefix();
    }

    /**
     * Create a new CustomizableThreadCreator with the given thread name prefix.
     *
     * @param threadNamePrefix the prefix to use for the names of newly created
     * threads
     */
    public CustomizableThreadCreator(String threadNamePrefix) {
        this.threadNamePrefix = (threadNamePrefix != null ? threadNamePrefix : getDefaultThreadNamePrefix());
    }

    /**
     * Specify the prefix to use for the names of newly created threads. Default
     * is "SimpleAsyncTaskExecutor-".
     */
    public void setThreadNamePrefix(String threadNamePrefix) {
        this.threadNamePrefix = (threadNamePrefix != null ? threadNamePrefix : getDefaultThreadNamePrefix());
    }

    /**
     * Return the thread name prefix to use for the names of newly created
     * threads.
     */
    public String getThreadNamePrefix() {
        return this.threadNamePrefix;
    }

    /**
     * Set the priority of the threads that this factory creates. Default is 5.
     *
     * @see java.lang.Thread#NORM_PRIORITY
     */
    public void setThreadPriority(int threadPriority) {
        this.threadPriority = threadPriority;
    }

    /**
     * Return the priority of the threads that this factory creates.
     */
    public int getThreadPriority() {
        return this.threadPriority;
    }

    /**
     * Set whether this factory is supposed to create daemon threads, just
     * executing as long as the application itself is running.
     * <p>Default is "false": Concrete factories usually support explicit
     * cancelling. Hence, if the application shuts down, Runnables will by
     * default finish their execution.
     * <p>Specify "true" for eager shutdown of threads which still actively
     * execute a Runnable.
     *
     * @see java.lang.Thread#setDaemon
     */
    public void setDaemon(boolean daemon) {
        this.daemon = daemon;
    }

    /**
     * Return whether this factory should create daemon threads.
     */
    public boolean isDaemon() {
        return this.daemon;
    }

    /**
     * Specify the name of the thread group that threads should be created in.
     *
     * @see #setThreadGroup
     */
    public void setThreadGroupName(String name) {
        this.threadGroup = new ThreadGroup(name);
    }

    /**
     * Specify the thread group that threads should be created in.
     *
     * @see #setThreadGroupName
     */
    public void setThreadGroup(ThreadGroup threadGroup) {
        this.threadGroup = threadGroup;
    }

    /**
     * Return the thread group that threads should be created in (or
     * {@code null}) for the default group.
     */
    public ThreadGroup getThreadGroup() {
        return this.threadGroup;
    }

    /**
     * Template method for the creation of a Thread.
     * <p>Default implementation creates a new Thread for the given Runnable,
     * applying an appropriate thread name.
     *
     * @param runnable the Runnable to execute
     * @see #nextThreadName()
     */
    public Thread createThread(Runnable runnable) {
        Thread thread = new Thread(getThreadGroup(), runnable, nextThreadName());
        thread.setPriority(getThreadPriority());
        thread.setDaemon(isDaemon());
        return thread;
    }

    /**
     * Return the thread name to use for a newly created thread.
     * <p>Default implementation returns the specified thread name prefix with
     * an increasing thread count appended: for example,
     * "SimpleAsyncTaskExecutor-0".
     *
     * @see #getThreadNamePrefix()
     */
    protected String nextThreadName() {
        int threadNumber = 0;
        synchronized (this.threadCountMonitor) {
            this.threadCount++;
            threadNumber = this.threadCount;
        }
        return getThreadNamePrefix() + threadNumber;
    }

    /**
     * Build the default thread name prefix for this factory.
     *
     * @return the default thread name prefix (never {@code null})
     */
    protected String getDefaultThreadNamePrefix() {
        return ClassUtils.getShortName(getClass()) + "-";
    }

    /**
     * Empty class used for a serializable monitor object.
     */
    private static class SerializableMonitor implements Serializable {
    }
}
